Method for decreasing misalignment of a printed circuit board and a liquid crystal display device with the printed circuit board

ABSTRACT

A method for improving a misalignment of a printed circuit board and a liquid crystal display device with the printed circuit board are disclosed. A printed circuit board having a substrate and PCB lands formed at a portion of the substrate in the horizontal direction is provided and a tape carrier package having TCP leads corresponding to the PCB lands is also provided. The intervals among the PCB lands are amended by the thermal expansion amount of the substrate. After the printed circuit board and the tape carrier package are aligned, the printed circuit board and the tape carrier package are connected to each other by the thermo-compression bonding process. The misalignment due to the thermo-compression bonding process can be improved, decreasing the processing failures and increasing the productivity.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a liquid crystal display device,more particularly to a liquid crystal display device having a liquidcrystal display panel that may decrease the failure of a tape automatedbonding (TAB) by decreasing occasions of a printed circuit board (PCB)when a ductile printed circuit board (PCB) misalignment such as a tapecarrier package (TCP) and the PCB are bonded by a thermo-compressionbonding method.

[0003] 2. Description of the Related Art

[0004] At present, a lot of display devices having minimized sizes andmore powerful functions are manufactured as the semiconductor technologyrapidly develops. The cathode ray tube (CRT) widely used for aninformation display device has some advantages such as high performanceand low cost. However, the CRT has disadvantages of its bulky size andpoor portability. The liquid crystal display (LCD) device has a smallersize and lighter weight. In addition, the LCD device can operate at lowpower. Hence the LCD device has been paid much attention as substitutefor the CRT and is now used for virtually all the information processingdevices.

[0005] In general, the LCD device includes a thin film transistor (TFT)substrate, a color filter substrate opposed to the TFT substrate and aliquid crystal display panel having a liquid crystal injected betweenthe TFT substrate and the color filter substrate. The LCD devicedisplays the information by utilizing a light modulation resulting fromthe variation of the optical property of the liquid crystal.

[0006] A plurality of gate lines and a plurality of data lines areintersectably formed on the TFT substrate and thin film transistors forswitching device and the picture electrode are formed in the intersectedregion.

[0007] The data line receives the gray voltage selected by a sourcedriving integrated circuit (IC), and then transfers the gray voltage tothe liquid crystal. The gate line opens or closes the thin filmtransistor for switching according to the on/off signal outputted form agate driving IC. At that time, in order to apply the driving signals tothe gate line and the data line, the printed circuit board (PCB)including various semiconductor devices and parts thereon, the drivingIC transferring the driving signals to the gate line and the data lineand the liquid crystal display panel indicating the information shouldbe connected one after another.

[0008] The methods for connecting the liquid crystal panel, the printedcircuit board and the driving IC are generally divided into a chip onglass (COG) mounting method and a tape automated bonding (TAB) mountingmethod.

[0009] In the COG mounting method, the liquid crystal display panel isconnected to the printed circuit board by using a connector such as aflexible printed circuit (FPC) after the driving IC is mounted on theliquid crystal display panel. Also, in the TAB mounting method, theliquid crystal display panel is connected to the printed circuit boardby using a tape carrier package (TCP) including a tape and the drivingIC mounted on the tape.

[0010] As for the conventional TAB mounting method, the liquid crystaldisplay panel is connected to the TCP by a thermo-compression bondingprocess and by using an anisotropic conductive film (ACF) and theprinted circuit board is connected to the TCP by a soldering process.However, the pitches of input leads of the TCP should decrease as thenumber of the input leads of the TCP increases and the size of the TCPis reduced. So the probability of short-circuits between the adjacentinput leads of the TCP increases when the printed circuit board and theTCP are combined together by the soldering process. Hence, the printedcircuit board and the TCP are now combined together by thethermo-compression bonding process.

[0011]FIG. 1 is a plane view for illustrating the conventional liquidcrystal display device including the printed circuit board and the tapecarrier package bonded together by the thermo-compression bondingprocess at high temperature.

[0012] Referring to FIG. 1, a liquid crystal display panel 10 receivesthe electrical signal from the outside, and then displays theinformation thereon. Printed circuit boards 20 and 30 are connected tothe liquid crystal display panel 10 and transfer the electrical signalto the liquid crystal display panel 10. Tape carrier packages 40 and 50connect the liquid crystal display panel 10 to the printed circuitboards 20 and 30 to drive the liquid crystal display panel 10.

[0013] The liquid crystal display panel 10 includes a TFT substrate 14and a color filter substrate 12 facing each other.

[0014] A plurality of gate lines (not shown) are disposed on the TFTsubstrate 14 along the length of the TFT substrate 14 and a plurality ofdata lines (not shown) are disposed on the TFT substrate 14 along thewidth of the TFT substrate 14. The gate lines and the data lines areintersecting each other. Gate input pads and data input pads (not shown)are respectively formed on each end of the gate lines and the data linesoutside the color filter substrate 12.

[0015] The printed circuit board composed of a gate printed circuitboard 20 electrically connected to the gate input pads through the TCP40 and a source printed circuit board 30 electrically connected to thedata input pads through the TCP 50.

[0016] A gate driving IC 42 and a source driving IC 52 that respectivelydrive the gate lines and the source lines are formed on the surface ofthe tape carrier packages 40 and 50.

[0017] Hereinafter, it will be described that a method for connectingthe liquid crystal display panel 10 to the printed circuit boards 20 and30 by using the tape carrier packages 40 and 50.

[0018] At first, after the anisotropic conductive film is attached tothe data pads and the gate pads, the output ends of the tape carrierpackages 40 and 50 are positioned on the surface of the anisotropicconductive film, and then the surfaces of the tape carrier packages 40and 50 are pressed by a thermo-compression device. Thus, the gate padsand the data pads and the output leads (not shown) of the tape carrierpackages 40 and 50 are electrically connected while the anisotropicconductive film composed of a thermoplastic resin is completelycompressed to the liquid crystal display panel 10 by thethermo-compression device.

[0019] Subsequently, after the anisotropic conductive film is attachedto the surface of the PCB land group (not shown) formed on the rearsurface of the printed circuit boards 20 and 30, the input leads (notshown) of the tape carrier packages 70 and 90 are respectively attachedto the rear surfaces of the printed circuit boards 20 and 30 by usingthe thermo-compression device. Hence, the input leads of the tapecarrier packages 40 and 50 are electrically connected to the PCB lands(not shown) of the printed circuit boards 20 and 30 while theanisotropic conductive film is hardened by the heat and the force of thethermo-compression device at high temperature.

[0020] In the above-described method, however, thermal expansions ofcomponents may misalign the printed circuit boards 20 and 30 from thetape carrier packages 40 and 50, causing bonding failures.

[0021]FIG. 2 is a plane view for showing the thermal expansiondirections of the printed circuit board and the tape carrier packageduring the thermo-compression bonding process. FIG. 2 shows the thermalexpansions of the source printed circuit board and the tape carrierpackage in FIG. 1.

[0022] As shown in FIG. 2, the printed circuit board 30 is thermallyexpanded from the point M horizontally dividing the printed circuitboard 30 into two portions to both ends thereof. The thermal expansionamount of the printed circuit board 30 is accumulated toward both endportions of the printed circuit board 30 so that the thermal expansionamounts of the end portions have the largest values. Also, the tapecarrier package 50 is thermally expanded from the point M′ horizontallydividing the tape carrier package 50 into two portions to both endsthereof and the thermal expansion amounts of the end portions have thelargest values.

[0023] Thus, though the PCB lands group (not shown) of the printedcircuit board 30 and the leads of the tape carrier package 50 arealigned to each other before the thermo-compression process, they getmisaligned during the thermo-compression process due to the thermalexpansion between the printed circuit board 30 and the tape carrierpackage 50. They are misaligned most in the right portion (A₁) of afirst TCP and the left portion of an eighth TCP (A₂).

[0024] In order to reduce the bonding failure between the TAB-IC causedby the misalignment, the thickness of the printed circuit board isincreased, or the composition of the printed circuit board is changed.However, those methods do not totally solve the misalignment problemwhen the pitches between the leads become closer.

SUMMARY OF THE INVENTION

[0025] It is therefore a first objective of the present invention toprovide a method for bonding a printed circuit board and a tape carrierpackage, which can decrease the occasions of misalignment due to thermalexpansions of the printed circuit board and the tape carrier packagewhen a TAB-IC is bonded by a thermo-compression bonding method.

[0026] It is a second objective of the present invention to provide aliquid crystal display device manufactured according to the above methodfor bonding the printed circuit board and the tape carrier package todecrease the misalignment.

[0027] To accomplish the first objective of the present invention, onepreferred embodiment of the present invention provides a method forbonding an adherent member to a printed circuit board comprising thesteps of providing the printed circuit board having a substrate and aplurality of a first conductive pattern groups formed at a peripheralportion of the substrate in the direction of the length of the substratewherein the first conductive pattern group adjusted according to athermal expansion quantity of the substrate where the first conductivepattern group is positioned, providing the adherent member having aplurality of a second conductive pattern group corresponding to thefirst conductive pattern group, aligning the adherent member and theprinted circuit board, and bonding the adherent member to the printedcircuit board by a thermo-compression bonding method.

[0028] Also, to accomplish the second objective of the presentinvention, another preferred embodiment of the present inventionprovides a liquid crystal display device including a printed circuitboard and a tape carrier package attached to each other by theabove-mentioned method.

[0029] According to the present invention, when the PCB lands arethermo-compressed with tape carrier packages by mean of shrinking thePCB lands of the printed circuit board by the thermal expansion of theprinted circuit board, the misalignment due to the thermal expansion ofthe printed circuit board can be decreased to sufficiently secure theprocessing margin, so the productivity can be improved by reducing theprocessing failure. Also, the degree of misalignment can be uniformlymaintained to enhance the control of the misalignment and to increasethe stability of the product.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above objectives and advantages of the present invention willbecome more apparent by describing in detail preferred embodimentsthereof with reference to the attached drawings:

[0031]FIG. 1 is a plane view illustrating a liquid crystal display panelincluding the conventional printed circuit board and a tape carrierpackage attached each other.

[0032]FIG. 2 is a plane view illustrating expansion directions of theconventional printed circuit board and the tape carrier package duringthermo-compression bonding at high temperature.

[0033]FIG. 3A is a plane view showing a shrinkage printed circuit boardin the pre-compression bonding state according to one embodiment of thepresent invention.

[0034]FIG. 3B is a plane view showing a tape carrier package in thepre-compression bonding state according to one embodiment of the presentinvention.

[0035]FIGS. 4A, 4B, 4C and 4D are graphs illustrating the misalignmentof the conventional printed circuit board at various temperatures.

[0036] FlG. 5A is a plane view illustrating the thermal expansion of theshrinkage printed circuit board on the basis of the left portions of afirst and a eighth tape carrier packages according to the presentinvention.

[0037]FIG. 5B is a plane view illustrating the measurement ofmisalignment on the A region in FIG. 5A.

[0038]FIG. 5C is a plane view illustrating the measurement ofmisalignment on the B region in FIG. 5A.

[0039]FIG. 6A is a plane view illustrating the thermal expansion of theshrinkage printed circuit board on the basis of the right portions of afirst and an eighth tape carrier packages according to the presentinvention.

[0040]FIG. 6B is a plane view illustrating the measurement of themisalignment on the A region in FIG. 5A.

[0041]FIG. 6C is a plane view illustrating the measurement of themisalignment on the B region in FIG. 6A.

[0042]FIG. 7A is a plane view showing a first printed circuit board landand the first tape carrier package in the alignment state after thermalexpansion.

[0043]FIG. 7B is a plane view showing an eighth printed circuit boardland and the eighth tape carrier package in the alignment state afterthermal expansion.

[0044]FIG. 8A is a graph comparing the experimental data of theshrinkage printed circuit board with the experimental data of theconventional printed circuit board.

[0045]FIG. 8B is a graph comparing the experimental data of themisalignment due to the thermal expansion of the shrinkage printedcircuit board with the experimental data of the misalignment of thethermal expansion of the conventional printed circuit board.

[0046]FIGS. 9A, 9B, 9C, 9D, 9E, 9F, 9G, 9H, 9I and 9J are graphsillustrating the misalignment of each sample on the basis of the centralline of the shrinkage printed circuit board according to the table 7.

[0047]FIGS. 10A, 10B, 10C, 10D and 10E are graphs illustrating themisalignment of each sample on the basis of the central line of theconventional printed circuit board according to the table 9.

[0048]FIG. 11 is a graph comparing the thermal expansion of each tapecarrier package of the shrinkage printed circuit board with the thermalexpansion of each tape carrier package of the conventional printedcircuit board.

[0049]FIG. 12 is a plane view showing a liquid crystal display deviceincluding the shrinkage printed circuit board and the tape carrierpackage bonded to each other by the thermo-compression bonding method ata high temperature according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] Hereinafter, the present invention will now be described morefully with reference to the accompanying drawings, in which preferredembodiments of the present invention are shown. The present inventionmay, however, be embodied in many different forms and should not beconstrued as being limited to the embodiments set forth herein.

[0051]FIGS. 3A and 3B are plane views showing the printed circuit boardand the tape carrier package according to one embodiment of the presentinvention.

[0052] Hereinafter, the minus (−) indicates the displacement toward theleft direction and the plus (+) represents the displacement toward theright direction.

[0053] Referring to FIG. 3A, a printed circuit board 100 according tothe present invention, has a substrate 110 and PCB land group 120 thatelectrically connects the substrate 110 to outside. Also, a drivingcircuit is formed on the printed circuit board 100 for operating theliquid crystal display device.

[0054] The PCB land group 120 is composed of a plurality of PCB lands120 a through 120 h. Each of the PCB lands 120 a to 120 h is shrunk by apredetermined dimension (hereinafter it is called the shrinkage design)in the direction of a point M dividing the substrate 110 into two partsalong the length of the substrate 110. The PCB lands 120 a through 120 hare defined as a first PCB land 120 a to a eighth PCB land 120 h spanfrom the left of the substrate 110. Also, an anisotropic conductive film(ACF) 130 is attached to the upper surfaces of the PCB lands 120 athrough 120 h.

[0055] The length of the printed circuit board 100 is generallyindicated as the distance from the right end of the eighth PCB land 120h corresponding to a eighth tape carrier package to the left end of thefirst PCB land 120 a corresponding to a first tape carrier package. Sothe printed circuit board 100 of the present invention has the shrunklength (hereinafter, the printed circuit board 100 is called as ashrinkage printed circuit board), when compared to the conventionalprinted circuit board.

[0056] The shrinkage amount of the shrinkage printed circuit board 100is determined by the degree of misalignment happening in theconventional printed circuit board according to one embodiment of thepresent invention. For this purpose, after the conventional printedcircuit board having a thickness of about 0.45t was thermo-compressedunder a pressure of about 172 kg f/cm² for about 20 seconds, the degreeof misalignment were respectively measured at the left and the right ofthe TCP as shown in Table 1. In the thermo-compression bonding process,Sample 1, Sample 2 and Sample 3 were respectively bonded by thethermo-compression bonding method at temperatures of about 415° C.,about 405° C., about 415° C. and about 420° C. FIG. 4 illustrates thegraphs according to the results shown in Table 1. TABLE 1 Degree ofmisalignment (μm) at each TCP of the conventional printed circuit boardat various temperatures. TCP1 TCP2 TCP3 TCP4 TCP5 TCP6 TCP7 TCP8 SampleLeft −58 −26 −34    1   13   12 60 63 1 Right −96 −81 −83 −53 −23 −29 1312 Sample Left −39 −61 −14   14   17   38 77 66 2 Right −96 −96 −63 −33−23  −3 18 36 Sample Left −41 −28 −27  −1    6   14 44 59 3 Right −88−74 −85 −58 −59 −30 −10    3 Sample Left −44 −46 −13   52   57   21 8181 4 Right −93 −97 −47    8    2 −20 26 31

[0057] As shown in FIG. 2, in the conventional printed circuit board,the first TCP and the eighth TCP are expanded the most due to thethermal expansion. Referring to FIG. 4, the degree of misalignment tendsto increase toward the right upper end and the misalignment occurs a lotin the left of the point M dividing the printed circuit board into thetwo portions rather than the right of the point M. The reason is thatthe thermal reaction properties in the left and the right portions ofthe printed circuit board are different from each other since theconventional printed circuit board is not symmetric in left and right.

[0058] Referring to Table 1 and FIG. 4, the TCP 1 and the TCP 8 aremisaligned most. The shrinkage of the PCB lands respectivelycorresponding to the TCP 1 and the TCP 8 can be determined. Hence, theshrinkage printed circuit board 100 is formed by determining thepositions of other PCB lands to have constant intervals in the leftportion and the right portion of the printed circuit board based on theshrinkage of the PCB lands respectively corresponding to the TCP 1 andthe TCP 8.

[0059] According to Table 1, the average of the regions where the TCP 1and the TCP 8 are positioned are −69.375 μm and 43.875 μm, respectively.Also, since the degree of misalignment in the left portion of theconventional printed circuit board is higher than the right portion ofthe printed circuit board as shown in FIG. 4, the PCB land 120 acorresponding to the TCP 1 200 a is shrunk toward the point M by thedimension of about 66.5 μm under the processing allowance of about 2.875μm and the PCB land 120 h corresponding to the TCP 200 h is shrunk bythe dimension of about 46.5 μm toward the point M under the processingallowance of about 2.125 μm. Thus, so the shrinkage printed circuitboard 100 has the shrunk dimension by the length of about 112.5 μm incomparison with the conventional printed circuit board.

[0060] Also, the thermal expansion amount of the left portion of theshrinkage printed circuit board 100 is larger than the thermal expansionamount of the right portion of the shrinkage printed circuit board 100depending on the shape of the shrinkage printed circuit board 100 sothat the distances among the PCB lands are set as 19 μm in the leftportion of the point M and 13 μm in the right portion of the point M.

[0061] Hence, in order to improve this misalignment according to the oneembodiment of the present invention, the dimensions of the PCB lands areshrunk as shown in FIG. 3A so that the shrinkage printed circuit board100 has the shrunk length by 112.5 μm compared with the length of theconventional printed circuit board.

[0062] Referring to FIG. 3B, the TCP unit 200 corresponding to the PCBland group 120 is fixed at the edge portion of the TFT substrate 300 byinterposing the ACF 250. The ACF 250 is the medium that electricallyconnects the TCP unit 200 to the TFT substrate 300. The TCP unit 200corresponds to the PCB lands 120 a through 120 h and consists of thefirst TCP 200 a through the eighth TCP 200 h from the left of the TCPunit.

[0063] The driving IC 220 is disposed at the central portion of the filmcomposed of the light transmitting polyamide and each TCP 200 a through200 h includes input lead 230 and output lead 240. The input lead 230connects the driving IC 220 to the printed circuit board 100 and theoutput lead 240 connects the driving IC 220 to the TFT substrate 300 byinterposing the ACF 250 thereto.

[0064] In this case, each of TCP 200 a through 200 h is formed by apredetermined interval to align in the position, before each PCB 120 athrough 120 h corresponding to each of the TCP 200 a through 200 h isshrunk. Hereinafter, the portion of the shrinkage printed circuit board100 where the input lead 230 and the output lead 240 are installed iscalled a horizontal portion while the portion of the shrinkage printedcircuit board 100 perpendicular to the horizontal portion is called avertical portion.

[0065] In the shrinkage printed circuit board 100 having theabove-described construction, the input lead 230 of the TCP 200 athrough 200 h is covered with the ACF 130 of the shrinkage printedcircuit board 100 by utilizing a movable stage and a fixing member. Atthat time, the center of each PCB land 120 a through 120 h is deviatedfrom the center of each TCP 200 a through 200 h by the shrinkage amountof each PCB land 120 a through 120 h, thereby forming a pre-compressionstate.

[0066] In the pre-compression state, the shrinkage printed circuit board100 and the TCP unit 200 are attached at a predetermined temperatureunder a predetermined pressure during the thermo-compression bondingprocess.

[0067] At that time, the PCB lands 120 a through 120 h are expandedtoward the left and the right ends of the substrate 110 centering aroundthe point M according to the thermal expansion of the substrate 110 tocompensate the shrinkage amount of each PCB land 120 a through 120 hwhen the shrinkage printed circuit board 100 is manufactured. Thus, themisalignment is decreased since each PCB 120 a through 120 h are wellaligned to each TCP 200 a through 200 h.

[0068] For verifying the misalignment, the shrinkage printed circuitboards are measured after selecting arbitrary ten shrinkage printedcircuit boards and putting them through the thermo-compression bondingprocess. Each shrinkage printed circuit board has a thickness of about0.45t and is thermo-compressed at a temperature of about 175° C. under apressure of about 3 MPa for about 20 seconds.

[0069] The left and the right thermal expansion directions of the TCP200 a through 200 h are different from the thermal expansion directionof the substrate 110. Therefore, individual misalignment occurs to theleft and right directions of the TCP 200 a through 200 h. So the leftmisalignment of the TCP unit 200 and the right misalignment of the TCPunit 200 are independently measured as shown in Table 2. TABLE 2Misalignment values (μm) measured at each TCP of the shrinkage printedcircuit board TCP1 TCP2 TCP3 TCP4 TCP5 TCP6 TCP7 TCP8 Sample Left −28 −9−21 31 29 33 67 82  1 Right −64 −42 −49 −28 −36 −27 22 38 Sample Left 5233 45 39 23 27 24 27  2 Right −25 −35 −38 −47 −64 −60 −44 −47 SampleLeft 43 36 19 −24 −25 −21 26 20  3 Right −48 −34 −56 −66 −78 −57 −45 −56Sample Left 43 53 39 46 56 53 53 65  4 Right −29 28 −35 38 31 34 43 24Sample Left 19 31 −29 24 −35 22 29 32  5 Right −69 −47 −71 −69 −66 −67−55 −48 Sample Left −66 −48 −42 −28 −24 −17 12 42  6 Right −113 −85 −79−76 −67 −57 −44 −15 Sample Left 93 83 59 68 66 75 77 82  7 Right 50 5423 24 −37 28 33 48 Sample Left 47 72 30 29 39 45 46 62  8 Right −33 −44−58 −59 −56 −52 −44 −27 Sample Left 133 106 102 89 100 88 94 85  9 Right77 72 52 45 43 46 50 37 Sample Left 24 18 −28 −28 25 26 −45 37 10 Right−62 −59 −65 −77 −58 −64 −83 −32

[0070] Assuming that the thermal expansion increases linearly and thethermal expansion of the tape carrier packages 200 a through 200 h areconstant, the value taken from TCP1 to TCP8 is presumed to be the totalthermal expansion of the shrinkage printed circuit board 100.

[0071] When the length of the PCB is I₀ before the thermo-compressionbonding process and the length of the PCB is I after thethermo-compression bonding process, the thermal expansion amount perunit length is generally expressed as the following equation (1):$\begin{matrix}{\frac{I - I_{0}}{I}\alpha \quad \Delta \quad t} & (1)\end{matrix}$

[0072] In the above equation (1), α means a thermal expansioncoefficient of the PCB and Δt indicates the difference between theinitial temperature and the final temperature. The thermal expansioncoefficient, however, depends on the materials when the temperaturerange is not so wide. Hence, the thermal expansion amount of the PCBincreases linearly with a constant rate at all the points of the initiallength of the PCB and both ends of the PCB expand the most.

[0073] Also, as will be described below, the thermal expansion amountsof the tape carrier packages can be presumed to have constant valuesconcerning the shrinkage printed circuit board 100 or the conventionalprinted circuit board during the thermo-compression bonding process.

[0074] As shown in Table 3, the average value of each thermal expansionamount of each TCP is about 37.3 μm (the standard deviation is 2) whenthe shrinkage printed circuit board 100 is thermo-compressed. Also, theaverage value of each thermal expansion amount of each TCP is about42.17 μm (the standard deviation is 0.988) when the conventional printedcircuit board is thermo-compressed as shown in Table 7.

[0075] According to the above-mentioned assumption, the differencebetween the measured thermal expansion amount of the first TCP 200 a andthe measured thermal expansion amount of the eighth TCP 200 h, both tapecarrier packages 200 a and 200 h respectively locating at end portionsof the shrinkage printed circuit board 100, is presumed to be the totalthermal expansion amount of the shrinkage printed circuit board 100.Such presumption will be described with reference to FIGS. 5 and 6 asfollows. Hereinafter, the left misalignment is measured based on eachleft portion of each TCP and the right misalignment is measured based oneach right portion of each TCP.

[0076]FIGS. 5A, 5B and 5C are plane views illustrating the presumptionof the total thermal expansion amount of the shrinkage printed circuitboard 100 concerning the measured misalignment amounts on the basis ofthe left portions of the first TCP 200 a and the eight TCP 200 h.

[0077] Referring to FIG. 5A, the expansion direction of the first TCP200 a is identical to the expansion direction of the shrinkage printedcircuit board 100. However,, the expansion direction of the eight TCP200 h is opposite to the expansion direction of the shrinkage printedcircuit board 100. FIG. 5B is a plane view illustrating the measurementof the misalignment of the A region in FIG. 5A. FIG. 5C is a plane viewillustrating the measurement of the misalignment of the B region in FIG.5A.

[0078] In FIG. 5B, a first real line 410 means the left end of the firstPCB land 120 a in the pre-compression state and a second real line 510indicates the left portion of the first TCP 200 a in the pre-compressionstate. Thus, the distance between the first real line 410 and the secondreal line 510 corresponds to the pre-adjustment made in thepre-compression state by shrinking the position of the first PCB land120 a toward the point M.

[0079] When the pre-compression process is performed concerning thefirst TCP 200 a and the first PCB land 120 a, the left end of the firstPCB land 120 a moves toward a first dotted line 420 due to the thermalexpansion of the substrate 100 and the left portion of the first TCP 200a also moves toward the second dotted line 520 for the same reason.Hence, after the thermo-compression bonding process, the first TCP 200 ais expanded by an interval (V₁) between the second real line 510 and thesecond dotted line 520. Also, the first PCB land 120 a expands by aninterval (P₁) between the first real line 410 and the first dotted line420. Then, the measured misalignment value becomes the interval (A₁)from the second dotted line 520 to the first dotted line 420. Therefore,the magnitude of the misalignment (A₁) measured at the left portion ofthe first TCP 200 a is expressed according to the following equation(2):

A ₁ =−P ₁−(−V ₁)   (2)

[0080] In Table 2, since the left misalignment value of the first TCP200 a is −28, the left end of the first PCB land 120 a is positioned ata position departed from the left portion of the first TCP 200 a byabout 28 μm toward the left direction after thermal expansion of thesubstrate 100.

[0081] In FIG. 5C, the first real line 610 means the left end of theeighth PCB land 120 h in the pre-compression state and the second realline 710 indicates the left portion of the eighth TCP 200 h in thepre-compression state. Thus, the distance between the first real line610 and the second real line 710 corresponds to the pre-adjustment madein the pre-compression state by shrinking the position of the eighth PCBland 120 h toward the point M.

[0082] When the pre-compression process is performed concerning theeighth TCP 200 h and the eighth PCB land 120 h, the left end of theeighth PCB land 120 h moves toward the first dotted line 620 due to thethermal expansion of the substrate 100 and the left portion of theeighth TCP 200 h also moves toward the second dotted line 720 due to thethermal expansion of the substrate 100. Hence, after thethermo-compression bonding process, the eighth TCP 200 h is expanded byan interval (V₈) between the second real line 710 and the second dottedline 720. The eighth PCB land 120 h also expands by an interval (P₈)between the first real line 610 and the first dotted line 620. Also, themeasured misalignment value becomes the interval (A₈) from the seconddotted line 720 to the first dotted line 620. Therefore, the magnitudeof the misalignment (A₈) measured at the left portion of the eighth TCP200 h is expressed according to the following equation (3):

A ₈ =P ₈−(−V ₈)   (3)

[0083] In Table 2, since the left misalignment value of the eighth TCP200 h is 82, the left end of the eighth PCB land 120 h is positioned ata position departed from the left portion of the eighth TCP 200 h byabout 82 μm in the right direction after thermal expansion of thesubstrate 100.

[0084] Hence, the following equation (4) can be obtained by taking theequation (2) from the equation (3):

A ₈ −A ₁ =P ₈ +P ₁   (4)

[0085] Therefore, the difference between the misalignment valuesmeasured at the left portions of the first TCP 200 a and the eighth TCP200 h is regarded as the total thermal expansion amount of the shrinkageprinted circuit board 100 generated during the thermo-compressionbonding process.

[0086]FIGS. 6A, 6B, and 6C are plane views illustrating the presumptionof the total thermal expansion amount of the shrinkage printed circuitboard 100 concerning the measured misalignment amounts based on theright portions of the TCP unit 200.

[0087] Referring to FIG. 6A, the expansion direction of the first TCP200 a is opposite to the expansion direction of the shrinkage printedcircuit board 100. However, the expansion direction of the eighth TCP200 h is identical to the expansion direction of the shrinkage printedcircuit board 100. FIG. 6B is a plane view illustrating the measurementof the misalignment of the C region in FIGS. 6A and 6C is a plane viewillustrating the measurement of the misalignment of the D region in FIG.6A.

[0088] In FIG. 6B, the first real line 430 means the right end of thefirst PCB land 120 a, in the pre-compression state and the second realline 530 indicates the right portion of the first TCP 200 a in thepre-compression state. Thus, the distance between the first real line430 and the second real line 530 corresponds to the pre-adjustment madein the pre-compression state by shrinking the position of the first PCBland 120 a toward the point M.

[0089] When the pre-compression process is performed concerning thefirst TCP 200 a and the first PCB land 120 a, the right end of the firstPCB land 120 a moves toward the first dotted line 440 due to the thermalexpansion of the substrate 100 and the right portion of the first TCP200 a also moves toward the second dotted line 540 for the same reason.Hence, after the thermo-compression bonding process, the first TCP 200 aexpands by an interval (W₁) between the second real line 530 and thesecond dotted line 540 and the first PCB land 120 a, corresponding tothe first TCP 200 a, expands by an interval (P₁) between the first realline 430 and the first dotted line 440. T hen, the measured misalignmentvalue becomes the interval (B₁) from the second dotted line 540 to thefirst dotted line 440. Therefore, the magnitude of the miss-alignment(B₁) measured at the right portion of the first TCP 200 a is expressedaccording to the following equation (5):

B ₁ =−P ₁−(W ₁)   (5)

[0090] In Table 2, since the right misalignment value of the first TCP200 a is −64, the right end of the first PCB land 120 a is positioned ata position departed from the right portion of the first TCP 200 a byabout 64 μm in the left direction after thermal expansion of thesubstrate 100.

[0091] In FIG. 6C, the first real line 630 means the right end of theeighth PCB land 120 h in the pre-compression state and the second realline 730 indicates the right portion of the eighth TCP 200 h in thepre-compression state. Thus, the distance between the first real line630 and the second real line 730 corresponds to the preadjustment madein the pre-compression state by shrinking the position of the eighth PCBland 120 h toward the point M.

[0092] When the pre-compression process is performed on the eighth TCP200 h and the eighth PCB land 120 h corresponding to the eighth TCP 200h, the right end of the eighth PCB land 120 h moves toward the firstdotted line 640 due to the thermal expansion of the substrate 100 andthe right portion of the eighth TCP 200 h also moves toward the seconddotted line 740 for the same reason. Hence, after the thermo-compressionbonding process, the eighth TCP 200 h is expanded by an interval (W₈)between the second real line 730. The second dotted line 740 and theeighth PCB land 120 h expands by an interval (P₈) between the first realline 630 and the first dotted line 640. Also, the measured misalignmentvalue becomes the interval (B₈) from the second dotted line 740 to thefirst dotted line 640. Therefore, the magnitude of the misalignment (B₈)measured at the right portion of the eighth TCP 200 h is expressedaccording to the following equation (6):

B ₈ =P ₈−(W ₈)   (6)

[0093] In Table 2, since the right misalignment value of the eighth TCP200 h is 38, the right end of the eighth PCB land 120 h is positioned ata position departed from the right portion of the eighth TCP 200 h byabout 38 μm in the right direction after the thermal expansion of thesubstrate 110.

[0094] Hence, the following equation (7) can be obtained by taking theequation (5) from the equation (6):

B ₈ −B ₁ =P ₈ +P ₁   (7)

[0095] Therefore, the difference between the misalignment valuesmeasured at the right portions of the first TCP 200 a and the eighth TCP200 h is regarded as the total thermal expansion amount of the shrinkageprinted circuit board 100 generated during the thermo-compressionbonding process.

[0096]FIGS. 7A and 7B are plane views showing the relative positionbetween the PCB land and the TCP concerning Sample 1 in Table 2 afterthe thermo-compression bonding process. FIG. 7A is a plane viewillustrating the alignment state between the first PCB land and thefirst TCP and FIG. 7B is a plane view showing the alignment statebetween the eighth PCB land and the eighth TCP.

[0097] Referring to FIGS. 7A and 7B, the total thermal expansion amountof the shrinkage printed circuit board 100 is directly obtained bytaking the measured misalignment value of the eighth TCP 200 h from themeasured misalignment value of the first TCP 200 a.

[0098] In this case, though the thermal expansion occurs in the sameshrinkage printed circuit board, the thermal expansion amount on theleft of the TCP unit (see the equation (4)) differs from the thermalexpansion amount on the right of the TCP unit (see the equation (7)).Due to the asymmetry of the shrinkage printed circuit board 100 aboutthe point M, such difference may cause the minute difference among theTCP unit 200 presumed acceptable as they have identical values and thedifference among the thermal reaction properties of the TCP unit, causesprocessing errors.

[0099] Consequently, the thermal expansion amounts of each sample inTable 2 can be presumed according to the equation 4 and 7, and thepresumed thermal expansion amounts are shown at column A in Table 3.TABLE 3 presumed thermal expansion (μm) of the shrinkage printed circuitboard and the misalignment amount (μm) of the shrinkage printed circuitboard according to the presumed thermal expansion. A B C D E F Sample 1Left 110 277114 92 18 9 130 Right 102 10 5 122 Sample 2 Left −25 277020−2 −23 −12  89 Right −22 −20 −10  92 Sample 3 Left −23 277015 −7 −16 −8 96 Right 8 1 1 111 Sample 4 Left 22 277008 −14 36 18 148 Right 53 67 34179 Sample 5 Left 13 277020 −2 15 8 127 Right 21 23 12 135 Sample 6 Left108 277084 62 46 23 158 Right 98 36 18 148 Sample 7 Left −11 277013 −9−2 −1 110 Right −2 7 4 119 Sample 8 Left 15 277020 −2 17 9 129 Right 6 84 120 Sample 9 Left −48 276967 −55 7 4 119 Right −40 15 8 127 Sample 10Left 13 277020 −2 15 8 127 Right 30 32 26 144

[0100] Meanwhile, since the conventional printed circuit board isdesigned as it has the standard length of 277134 μm after thestandardized process, the shrinkage printed circuit board 100 having theposition of the PCB land group shrunk by 112.5 μm has the standardlength of 277022 μm after the standardized process in comparison withthe conventional printed circuit board. Hereinafter, the shrinkageprinted circuit board will be called as the standard printed circuitboard when shrinkage printed circuit board goes through the standardizedprocess.

[0101] The measured lengths of the shrinkage printed circuit boards 100for experiment are shown at column B in Table 3 and the lengthdeviations of the PCB are presented by taking the standard length fromthe measured length of the shrinkage printed circuit boards 100 atcolumn C in Table 3.

[0102] In general, the length deviation of the PCB is known that itaffects the misalignment regarding of the shrinkage design. Therefore,the PCB allowance control should be needed in the range of ±70 μmconcerning the product having the pitch of above 400 μm and the PCBallowance control should be needed in the range of ±50 μm concerning theproduct having the pitch of below 400 μm. Hence, Sample 1 is deviatedfrom the allowance, judging from the basis of the PCB allowance havingthe above range.

[0103] The thermal expansion amounts of the shrinkage printed circuitboard 100 are presented at column D in Table 3 after the lengthdeviations of the PCB are amended. The length deviations of the PCBnumerically affect the misalignment. So the value obtained by taking thelength deviations at the column C from the expansion amount at column Ameans the total thermal expansion amount of the shrinkage printedcircuit board 100, when the shrinkage printed circuit board 100 for eachsample has a standard length.

[0104] Also, the shrinkage printed circuit board 100 can be treated asit has the length deviation of about 112.5 μm comparing with theconventional printed circuit board so that the presumed thermalexpansion amount can be obtained about the conventional printed circuitboard when the initial shrinkage amount of 112.5 μm is added to thetotal expansion amount at column D. Such presumed thermal expansionamounts are presented at column E in Table 3.

[0105] In the meantime, when the standard shrinkage printed circuitboard is thermo-compressed, the misalignment only depending on thethermal expansion of the printed circuit board corresponds to the valueobtained by halving the total thermal expansion amount in case ofneglecting deviation of the instruments, expansion of the tape carrierpackage and other factors. The reason is that the thermal expansion ofthe printed circuit board occurs in the left and the right directionscentering around the point M. The misalignment values of the shrinkageprinted circuit board 100 having the standard length are shown at columnE in Table 3.

[0106] Therefore, when the shrinkage printed circuit board 100 of thepresent embodiment is thermo-compressed, the standard deviation is about2.64 and the average misalignment of 7.9 μm is occurred. Also, if theconventional standard printed circuit board is not shrunk, the averagethermal expansion amount becomes about 127 expansion amount at column D.Such presumed thermal expansion amounts are presented at column E inTable 3.

[0107] In the meantime, when the standard shrinkage printed circuitboard is thermo-compressed, the misalignment only depending on thethermal expansion of the printed circuit board corresponds to the valueobtained by halving the total thermal expansion amount in case ofneglecting deviation of the instruments, expansion of the tape carrierpackage and other factors. The reason is that the thermal expansion ofthe printed circuit board occurs in the left and the right directionscentering around the point M. The misalignment values of the shrinkageprinted circuit board 100 having the standard length are shown at columnE in Table 3.

[0108] Therefore, when the shrinkage printed circuit board 100 of thepresent embodiment is thermo-compressed, the standard deviation is about2.64 and the average misalignment of 7.9 μm is occurred. Also, if theconventional standard printed circuit board is not shrunk, the averagethermal expansion amount becomes about 127 μm.

[0109] Meanwhile, in order to compare the improvement of themisalignment generated in the shrinkage printed circuit board, themisalignment values are measured at the left and the right portions ofthe TCP after sampling the conventional printed circuit boards. Suchexperiments are performed on 5 conventional printed circuit boards. Thecomposition and the thickness of the conventional printed circuit boardare identical to those of the shrinkage printed circuit board and theprocessing conditions and the signs for the conventional printed circuitboard are also identical to those for the shrinkage printed circuitboard. The measured misalignment values from the experiment are shown inthe following Table 4. TABLE 4 The misalignment values (μm) measured ateach TCP of the conventional printed circuit board TCP1 TCP2 TCP3 TCP4TCP5 TCP6 TCP7 TCP8 Sample Left −34 −29 −30 −21 −25 −26 33 42 1 Right−88 −59 −62 −71 −66 −63 −54 −50 Sample Left −68 −66 −53 −47 −33 35 46 452 Right −110 −101 −85 −84 −78 −50 −39 −49 Sample Left −44 −42 −41 −30−16 31 27 53 3 Right −83 −79 −67 −67 −69 −54 −48 −39 Sample Left −67 −61−30 −48 −39 −35 −22 33 4 Right −111 −108 −69 −81 −83 −77 −71 −53 SampleLeft −55 −48 −39 −29 26 37 34 35 5 Right −103 −89 −72 −72 −64 −53 −52−57

[0110] The values obtained by taking TCP 1 from TCP 8 is presumed as thetotal thermal expansion amount of the conventional printed circuit boardsuch as the shrinkage printed circuit board. The calculated misalignmentamounts of the conventional printed circuit board are presented in Table5 based on the measured misalignment values in Table 4. TABLE 5 presumedthermal expansion (μm) of the conventional printed circuit board and themisalignment amount (μm) of the conventional printed circuit boardaccording to the presumed thermal expansion. A B C D E Sample 1 Left 76277058 −76 152 76 Right 38 114 57 Sample 2 Left 113 277104 −30 143 72Right 61 91 46 Sample 3 Left 97 277091 −43 140 70 Right 50 93 47 Sample4 Left 100 277089 −45 145 73 Right 58 103 52 Sample 5 Left 90 277096 −38128 64 Right 46 84 42

[0111] In Table 5, column A means the thermal expansion amounts of theconventional printed circuit board presumed from the measuredmisalignment values in Table 4 and column B indicates the measuredlengths of the samples utilized during the experiment. Column C meansthe values obtained by the standard length of the conventional printedcircuit board (that is, 277134 μm) from the measured lengths andrepresents the length deviations concerning the conventional printedcircuit board.

[0112] Hence, the thermal expansion amounts amended by the lengthdeviations of the PCB about the samples of the conventional printedcircuit board correspond to the values obtained by taking the values ofthe column C from the values of column A. Such presumed thermalexpansion amounts are shown at column D in Table 5 and the conventionalprinted circuit board expands by the average thermal expansion amount of119 μm while the standard deviation is 25.4.

[0113] The misalignment due to the thermal expansion of the conventionalprinted circuit board are presented at column E in Table 5. Since thethermal expansion of the conventional printed circuit board occurs inthe left and the right directions centering around the half point M, themisalignment amounts correspond to one half of the presumed thermalexpansion amount at the column D, And the average misalignment amount isabout 60 μm while the standard deviation is 4.0.

[0114] Therefore, if the misalignment amount due to the thermalexpansion of the shrinkage printed circuit board of the presentembodiment in Table 3 is compared with the misalignment amount due tothe thermal expansion of the conventional printed circuit board in Table5, the decrease in misalignment according to the present embodiment canbe clearly verified.

[0115] According to the present embodiment, the decrease in misalignmentis verified at a temperature of 175° C. But, the decrease inmisalignment is of course verified in a temperature range that thethermal expansion of the printed circuit board is largely generated. Anepoxy, with which the printed circuit board is made, is generallytransformed into a glass at a temperature about 140° C. (transitiontemperature of the PCB), and therefore, the decrease in misalignment isalways verified in a thermo-compression bonding process performed at atemperature more than the transition temperature of the PCB. However, ata temperature more than 200° C., adhesive force is remarkably loweredbecause of an over-hardness characteristic of the ACF film.Consequently, the decrease of the misalignment is conspicuously verifiedin a range of the temperature between 140° C. and 200° C.

[0116]FIGS. 8A and 8B are graphs comparing the experimental data of theshrinkage printed circuit board of the present invention with theexperimental data of the conventional printed circuit board. FIG. 8A isa graph comparing the thermal expansion amount of the shrinkage printedcircuit board of the present invention with the thermal expansion amountof the conventional printed circuit board. FIG. 8B is a graph comparingthe misalignment amount due to the shrinkage printed circuit board ofthe present invention with the misalignment amount due to theconventional printed circuit board.

[0117] Referring to FIG. 8A, column D in Table 5 and column A in Table3, the average thermal expansion amount of the conventional printedcircuit board is about 119 μm and the average thermal expansion amountof the shrinkage printed circuit board is about 127 μm, so both thermalexpansion amounts have similar values. Hence, it is identified that theshrinkage of the substrate length does not much affect the thermalexpansion of the substrate.

[0118] Referring FIG. 8B, column D in Table 5 and column A in Table 3,however, the improvement effect of the misalignment due to the thermalexpansion of the substrate can be identified. While the averagemisalignment amount of the conventional standard printed circuit boardis 60 μm, the average misalignment amount of the shrinkage standardprinted circuit board is 7.9 μm to verify the great improvement of themisalignment in the shrinkage standard printed circuit board accordingto the present invention.

[0119] Meanwhile, the thermal expansion amount of the printed circuitboard is accumulated toward both left and right end portions of theprinted circuit board, so the generated misalignment amount is increasedtoward both left and right end portions of the printed circuit board.Such intention is already identified as the inclination is increasedtoward the right ends of the graphs in FIG. 4.

[0120] In the shrinkage printed circuit board 100 according to thepresent invention, the intervals among the PCB lands at the left and theright portions of the substrate 110 centering around the point M aredifferently set one after another, thereby constantly maintaining themisalignment amount generated in each of TCP 200 a through 200 h. Theconstant misalignment amount will be identified as follows by utilizingthe measured data in Tables 2 and 4.

[0121] In Table 2, the misalignment amount is measured on the basis ofeach edge of TCP 200 a through 200 h for the convenience of themeasurement. However, the precise misalignment amount should be measuredon the basis of each PCB land 120 a through 120 h and the center of eachlead of TCP 200 a through 200 h because the misalignment means theirregularity among conductive patterns for exchanging the electricalsignals between the printed circuit board and the tape carrier package.

[0122] Therefore, after the widths of each PCB land 120 a through 120 hand each TCP lead 200 a through 200 h are measured, the calculatedmisalignment values on the basis of the center of each TCP lead 200 athrough 200 h are presented in Table 7. In the samples of shrinkageprinted circuit board, the measured width of each PCB land 120 a to 120h and the measured width of each TCP lead 200 a to 200 h are shown inthe following Table 6. TABLE 6 The widths (μm) of the PCB land and theTCP lead of the shrinkage printed circuit board measured width of land(a) width of lead (b) (a − b)/2 Sample 1 195 170 12.5 Sample 2 215 22.5Sample 3 215 22.5 Sample 4 215 22.5 Sample 5 220 25 Sample 6 200 15Sample 7 220 25 Sample 8 220 25 Sample 9 220 25 Sample 10 215 22.5

[0123] As shown in Table 6, the measured width of the land is obtainedby measuring the real width of the PCB land of each sample and the widthof the lead is obtained by measuring the real width of the TCP lead ofeach sample. The widths of the leads are minutely various so that thewidth of the leads are treated as constants for all the samples.

[0124] Thus, though the difference between the measured width of theland and the width of the lead (hereinafter, it is called the widthdifference) is the value having no connection with the misalignment, thewidth difference is included in the measured misalignment value in Table2. The measured misalignment values in Table 2 are obtained on the basisof each TCP 200 a through 200 h and each TCP 200 a through 200 h isthermally expanded in the left and the right directions centering aroundthe point dividing each TCP 200 a through 200 h into two portions in thelengthwise direction of each TCP 200 a through 200 h. So two halves ofthe width difference are respectively included in the left and the rightportions of each TCP 200 a through 200 h centering around the pointdividing each TCP lead into two portions in the lengthwise direction ofeach TCP lead.

[0125] Therefore, the value obtained by halving the width differencefrom the measured misalignment value corresponds to the misalignmentvalue generated on the basis of the center of each TCP 200 a through 200h. In Table 2, half the width difference is added to the measuredmisalignment value in the left direction and half the width differenceis taken from the measured misalignment value in the right direction, sothe absolute misalignment value is reduced by half the width differencecompared with the measured misalignment value in Table 2. The calculatedmisalignment values on the basis of the center of the shrinkage printedcircuit board obtained the above method are shown in Table 7. TABLE 7the misalignment values (μm) on the basis of the center of the shrinkageprinted circuit board TCP1 TCP2 TCP3 TCP4 TCP5 TCP6 TCP7 TCP8 SampleLeft −16 4 −9 19 17 21 55 70  1 Right −52 −30 −37 −16 −24 −15 10 26Sample Left 30 11 23 17 1 5 2 5  2 Right −3 −13 −16 −25 −42 −38 −22 −25Sample Left 21 14 −4 −2 −3 2 4 −3  3 Right −26 −12 −34 −44 −56 −35 −23−34 Sample Left 21 31 17 24 34 31 31 43  4 Right −7 6 −13 13 9 12 21 2Sample Left −6 6 −4 −1 −10 −3 4 7  5 Right −44 −22 −46 −44 −41 −42 −30−23 Sample Left −51 −33 −27 −13 −9 −2 −3 27  6 Right −98 −70 −64 −61 −52−42 −29 0 Sample Left 68 58 34 43 41 50 52 57  7 Right 25 29 −2 −1 −12 38 23 Sample Left 22 47 5 4 14 20 21 37  8 Right −8 −19 −33 −34 −31 −27−19 −2 Sample Left 108 81 77 64 75 63 69 60  9 Right 52 47 27 20 18 2125 12 Sample Left 2 −5 −6 −6 3 4 −23 15 10 Right −40 −37 −43 −55 −36 −42−61 −10

[0126] The following Table 9 shows the misalignment values amended onthe basis of the center of each TCP lead by using the misalignmentamounts measured on the basis of the end portions of each TCP in Table 4according to the above-described method. In this case, the measuredvalues of each PCB land and each TCP lead are presented in TABLE 8 Thewidths (μm) of the PCB land and the TCP lead of the conventional printedcircuit board measured width of land (a) width of lead (b) (a − b)/2Sample 1 210 170 20 Sample 2 215 22.5 Sample 3 210 20 Sample 4 210 20Sample 5 210 20 Sample 6 220 25

[0127] TABLE 9 The misalignment values (μm) on the basis of the centerof the conventional printed circuit board TCP1 TCP2 TCP3 TCP4 TCP5 TCP6TCP7 TCP8 Sample Left −14 −9 −10 −1 −5 −6 13 22 1 Right −68 −39 −42 −51−46 −43 −34 −30 Sample Left −46 −44 −31 −25 −11 13 23 23 2 Right −88 −79−63 −62 −56 −28 −17 −27 Sample Left −24 −22 −21 −10 4 11 7 33 3 Right−63 −59 −47 −47 −43 −34 −28 −13 Sample Left −47 −41 −10 −28 −19 −15 −213 4 Right −91 −88 −49 −61 −63 −57 −51 −33 Sample Left −35 −28 −19 −9 617 14 15 5 Right −83 −69 −52 −52 −44 −33 −32 −37 Sample Left −38 −11 −20−3 12 15 37 52 6 Right −79 −56 −56 −43 −27 −29 −7 6

[0128]FIGS. 9A through 9I are graphs for showing the misalignment valuesin Table 7 and each graph illustrates the misalignment of each sample onthe basis of the center of each sample.

[0129] While the graphs of FIGS. 10A through 10E show the misalignmentamounts of the conventional printed circuit board generally having theinclinations toward the right ends of the graphs, the graphs of FIGS. 9Athrough 9I show the misalignment amounts of the shrinkage printedcircuit board samples according to the present invention approximatelyhaving the inclination parallel to the axis indicating the TCP.

[0130] Hence, the intervals among the PCB lands at the left portion ofthe shrinkage printed circuit board 100 are differently set from theintervals among the PCB lands at the right portion of the shrinkageprinted circuit board 100, thereby maintaining the magnitudes of themisalignment generated in each TCP 200 a through 200 h to have constantvalues after the thermo-compression bonding process. Also, it can beprevented that the excessive thermal expansions of each TCP 200 athrough 200 h generated by accumulating the thermal expansion in thefirst TCP 200 a and the eighth TCP 200 h.

[0131] In the meantime, the misalignment values in Tables 7 and 9 aregenerated on the basis of the center of each TCP 200 a through 200 h, sothe difference between the left misalignment value and the rightmisalignment value in the same TCP corresponds to the thermal expansionamount generated during the thermo-compression bonding process for theTCP. Thus, Tables 10 and 11 show the thermal expansion amount of eachTCP 200 a through 200 h calculated by utilizing the data in Tables 7 and9 concerning the shrinkage printed circuit board and the conventionalprinted circuit board. TABLE 10 The thermal expansion amounts (μm) ofthe TCP in the shrinkage printed circuit board Aver- TCP1 TCP2 TCP3 TCP4TCP5 TCP6 TCP7 TCP8 age Sample 36 33 28 34 40 35 45 44 37  1 Sample 3223 38 41 42 42 23 29 34  2 Sample 46 25 30 42 53 36 26 31 36  3 Sample27 25 29  8 25 19 10 41 23  4 Sample 38 28 42 43 31 39 34 30 36  5Sample 47 37 37 48 43 40 26 27 38  6 Sample 43 29 36 44 53 47 44 34 41 7 Sample 30 66 38 38 45 47 40 39 43  8 Sample 56 34 50 44 57 42 44 4847  9 Sample 41 32 37 49 38 45 38 24 38 10

[0132] TABLE 11 the thermal expansion amounts (μm) of the TCP in theconventional printed circuit board Aver- TCP1 TCP2 TCP3 TCP4 TCP5 TCP6TCP7 TCP8 age Sam- 54 38 32 50 41 37 47 52 43.875 ple 1 Sam- 42 35 32 3745 40 39 49 39.875 ple 2 Sam- 39 37 26 37 47 45 35 46 39 ple 3 Sam- 4447 39 33 44 42 49 46 43 ple 4 Sam- 48 41 33 43 50 50 46 52 45.375 ple 5Sam- 41 45 36 40 39 44 44 46 41.875 ple 6

[0133] As shown in Table 10, the average thermal expansion amountgenerated in the TCP is about 37 μm during the thermo-compressionbonding process for the shrinkage printed circuit board and the standarddeviation is 9.9. However, the average thermal expansion amountgenerated in the TCP is about 42 μm during the thermo-compressionbonding process for the conventional printed circuit board and thestandard deviation is 6.4.

[0134]FIGS. 9A through 9I are the graphs comparing the results in Table10 with the results in Table 11.

[0135] Referring to FIGS. 9A through 9I, Tables 10 and 11, assume thatthe tape carrier packages expand uniformly unlike the conventionalprinted circuit board and also the expansion of the printed circuitboard and the expansion of the tape carrier package are independent fromeach other. The uniform expansion of the tape carrier package is alreadymentioned in the above description for the shrinkage printed circuitboard as assumption according to the present invention.

[0136] According to the data in Tables 10 and 11, the average expansionamount of each TCP 200 a through 200 h is about 40 μm and themisalignment amount due to the expansion of each TCP 200 a through 200 his about 20 μm. Since the printed circuit board and the tape carrierpackage expand independently from each other, the shrinkage design forthe tape carrier package should be considered, separate from theshrinkage design for the printed circuit board.

[0137] Hence, when the shrinkage printed circuit board 100 and the tapecarrier package are combined by the thermo-compression bonding process,the occasions of misalignment due to the thermal expansion of theprinted circuit board can be remarkably reduced, thereby increasing theproductivity by reducing the failure during the bonding process.

[0138] As for the above-described embodiment of the present invention,though the printed circuit board is combined with the tape carrierpackage, a ductile circuit board can be used instead of the tape carrierpackage and also the numbers of the PCB land and the tape carrierpackage may be arbitrarily selected according to their uses andfunctions.

[0139]FIG. 12 is a plane view showing the liquid crystal display panelincluding the shrinkage printed circuit board and the tape carrierpackage combined together by the thermo-compression bonding process athigh temperature.

[0140] Referring to FIG. 12, the liquid crystal display panel 50receives the electrical signal from outside and displays theinformation, the shrinkage printed circuit boards 60, 80 connected tothe liquid crystal display panel 50 transfers the electrical signal tothe liquid crystal display panel 50, and the tape carrier packages 70,90 connects the liquid crystal display panel 50 to the shrinkage printedcircuit boards 60, 80 to operate the liquid crystal display panel 50.

[0141] The liquid crystal display panel 50 includes the thin filmtransistor substrate 52 and the color filter substrate 51 facing thethin film transistor substrate 52.

[0142] A plurality of gate lines (not shown) are disposed in a line onthe thin film transistor substrate 52 along the width of the thin filmtransistor substrate 52 and a plurality of data lines (not shown) aredisposed in a line to intersect the gate lines. The data lines aredisposed on the thin film transistor substrate 52 along the length ofthe thin film transistor substrate 52. Data input pads and gate inputpads are respectively formed on the gate and the data lines exposed fromthe color filter substrate 51.

[0143] The shrinkage printed circuit boards 60 and 80 are composed ofthe source shrinkage printed circuit board 60 electrically connected tothe data input pads by means of the tape carrier package 70 and the gateshrinkage printed circuit board 90 electrically connected to the gateinput pads by means of the tape carrier package 90.

[0144] The data driving integrated circuit (IC) 72 and the sourcedriving IC 92 for driving the data and the gate lines are formed on thesurface of the tape carrier packages 70 and 90.

[0145] It will be described that the method for connecting the shrinkageprinted circuit boards 60 and 80 to the liquid crystal display panel 50by means of the tape carrier packages 70 and 90.

[0146] At first, after the anisotropic conductive film (not shown) isattached to the data and the gate input pads, the output ends of thetape carrier packages 70 and 90 are positioned on the surface of theanisotropic conductive film, and then the surfaces of the tape carrierpackages 70 and 90 are pressed by using a thermo-compression device.Thus, the gate and the data input pads and the output leads (not shown)are electrically connected while the anisotropic conductive filmcomposed of the thermoplastic resin is completely compressed to theliquid crystal display panel 50 by the thermo-compression device.

[0147] Subsequently, after the anisotropic conductive film is attachedto the surface of the PCB land group formed on rear surface of theshrinkage printed circuit boards 60 and 80, the input leads (not shown)of the tape carrier packages 70 and 90 are attached to the rear surfacesof the shrinkage printed circuit boards 60 and 80 by using thethermo-compression device. Hence, the input leads of the tape carrierpackages 70 and 90 are electrically connected to the PCB lands (notshown) of the shrinkage printed circuit boards 60 and 80, while theanisotropic conductive film is hardened by the heat and the force of thethermo-compression device at high temperature.

[0148] At that time, as it is described above, the misalignment amountsbetween the shrinkage printed circuit boards 60 and 80 and the tapecarrier packages 70 and 90 corresponding to the shrinkage printedcircuit boards 60 and 80 are uniformly generated and the averagemisalignment value becomes 8 μm.

[0149] After the back light assembly is installed beneath the liquidcrystal display panel 50, the liquid crystal display device is completedby fixing the liquid crystal display panel and the back light assemblyto the mold frame.

[0150] According to the present invention, when the PCB lands arethermo-compressed with tape carrier packages by shrinking the PCB landsof the printed circuit board by the thermal expansion of the printedcircuit board, the misalignment due to the thermal expansion of theprinted circuit board can be decreased to sufficiently secure theprocessing margin, so the productivity can be improved by reducing theprocessing failure. Also, the misalignment amount can be uniformlymaintained to enhance the probability for controlling the misalignmentand to increase the stability of the product.

[0151] While the present invention has been particularly shown anddescribed with reference to preferred embodiments thereof, it will beunderstood by those skilled in the art that various changes in form anddetail may be effected therein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for bonding an adherent member to aprinted circuit board comprising the steps of: providing the printedcircuit board having a substrate and a plurality of a first conductivepattern group formed at a peripheral portion of the substrate in thedirection of the length of the substrate wherein the first conductivepattern group is adjusted according to a thermal expansion degree of thesubstrate where the first conductive pattern group is positioned;providing the adherent member having a plurality of a second conductivepattern group corresponding to the first conductive pattern group;aligning the adherent member and the printed circuit board each other;and bonding the adherent member to the printed circuit board by athermo-compression bonding method.
 2. The method of claim 1, wherein theadjusted amount of the first conductive pattern group has the largestvalue at both ends of the substrate and the adjusted amount of the firstconductive pattern group decreases toward a point dividing the substrateinto two portions.
 3. The method of claim 1, wherein a thermal reactionproperty of a first half portion of the substrate is different from athermal reaction property of a second half portion of the substrate whenthe substrate is divided lengthwise.
 4. The method of claim 3, whereinan adjusted amount of the first conductive pattern group positioned atthe first portion of the substrate is larger toward the point than anadjust amount of the first conductive pattern group positioned at thesecond portion of the substrate wherein the thermal reaction property ofthe first portion of the substrate is larger than the thermal reactionproperty of the second portion of the substrate.
 5. The method of claim3, wherein intervals among the first conductive pattern group positionedat the first portion of the substrate is larger than intervals among thefirst conductive pattern group positioned at the second portion of thesubstrate wherein the thermal reaction property of the first portion ofthe substrate is larger than the thermal reaction property of the secondportion of the substrate.
 6. The method of claim 1, wherein thethermo-compression bonding is performed through interposing ananisotropic conductive film between the printed circuit board and theadherent member.
 7. The method of claim 1, wherein the second conductivepattern group has intervals aligned with the first conductive patterngroup before the first conductive pattern group is adjusted.
 8. Themethod of claim 1, wherein the thermo-compression bonding is performedat a temperature of about 140 to 200° C.
 9. The method of claim 1,wherein the printed circuit board is connected to a thin film transistorsubstrate of a liquid crystal display device.
 10. The method of claim 1,wherein the adherent member is a tape carrier package.
 11. A liquidcrystal display device, comprising: a liquid crystal display panelhaving a thin film transistor substrate and a color filter substrateattached to the thin film transistor substrate by interposing a liquidcrystal between the color filter substrate and the thin film transistorsubstrate; a printed circuit board electrically connected to the liquidcrystal display panel; and an adherent member electrically connectingthe liquid crystal display panel to the printed circuit board to operatethe liquid crystal display panel, the adherent member attached to theprinted circuit board by a thermo-compression bonding method, wherein amisalignment amount of a conductive pattern group of an output of theprinted circuit board is identical to a misalignment amount of aconductive pattern group of an input of the adherent member.
 12. Theliquid crystal display device as claimed in claim 11, wherein a thermalreaction property of one half portion of the printed circuit board isdifferent from a thermal reaction property of the other half portion ofthe printed circuit board when dividing the printed circuit boardlengthwise.